This study examines the factors associated with the effective transport of a complex family-based mental health treatment, Multisystemic Therapy (MST), to community settings. As such, the study directly addresses major gaps in both clinical (psychotherapy) and mental health services research pertaining to the translation of efficacious treatments to effective mental health services. MST has proven effective in improving child behavior and family functioning in randomized trials with youth experiencing serious clinical problems. In three randomized trials with violent and chronic juvenile offenders, MST reduced long-term rates of rearrest and out-of-home placement and improved child behavior and family functioning. Earlier randomized trials demonstrated the promise of MST in treating child abuse/neglect and juvenile sex offenders, and an ongoing study is evaluating its effectiveness as an alternative to psychiatric hospitalization. In response to demand from policy makers and providers to develop MST programs, 27 programs serving 1500 youth and families annually have been established in 8 states and Canada. Recent research on MST has demonstrated a significant association between clinicians' adherence to the MST treatment protocol and favorable outcomes for youth. Thus, the foremost challenge in transporting the model and its favorable outcomes to usual care settings is determining the organizational and extra- organizational conditions that support the fidelity of MST interventions. Specifically, this study will examine the child and outcomes associated with MST as delivered by clinicians in 26 programs. Participants will be 2550 youth and families referred to MST programs and the clinicians and administrators employed by those programs. A multi-method multi-source measurement battery will be used to examine the organizational and extra-organizational factors thought to support fidelity to MST and concomitant child outcomes. The aims of this study are to: 1). Document the relationship between clinician adherence to a specific treatment model and child outcomes in usual care settings; 2). Examine the impact of intra-organizational variables on clinician adherence; 3). Examine the extent to which organizational variables relevant to transportability are influenced by selected extra-organizational factors; 4). Examine the influence of clinician variables on adherence; 5). Test a mediation model of treatment effectiveness in which the impact of intra- and extra-organizational factors and individual clinician variables on outcomes is mediated by clinician adherence.